OBJECTIVETo analyze the stress distribution in the abutment periodontal ligament of posterior cantilever bridge under transient dynamic loads using a three-dimensional finite element(FE) model.

METHODSA cantilever bridge using 5, 6 as abutments to restore missing 7 was designed, and its FE model was established and loaded with dynamic loads. The loads were set as 250 N occlusal forces loaded at different positions on the cantilever, and in different directions to simulate the masticatory cycle. FE analysis was conducted on the ANSYS to analyze stress distributions in abutment periodontal ligament under dynamic loads. Stress-time curves were traced to understand the biomechanical behavior of abutment periodontal ligament.

RESULTSWith loading and unloading time accumulated, the stress value in the abutment periodontal ligament increased gradually. Loads in lateral direction induced peak value stress in a masticatory cycle. There was little residual stress in the end of unloading phase. The maximum stress concentrated in abutment periodontal ligament adjacent to the missing tooth. Without restoration abutment periodontal ligament was mainly under compressive stress. However, when 7 was restored with a cantilever bridge, tensile stress was shown in the mesial cervical area of 5, Three masticatory cycles were simulated, and stress values in abutment periodontal ligaments increased with the number of masticatory cycles. But the differences of the stress between different masticatory cycles were not significant.

CONCLUSIONSIn the mastication movement, lateral loads induce maximum stress in abutment periodontal ligament. Cantilever fixed bridge design is more demanding for the periodontal condition of the abutment adjacent to the missing tooth than for the other abutment. When loaded with continuous masticatory force, the stress concentration does not increase significantly. Therefore, cantilever bridge is one of the feasible choices to restore missing lower second molar.

Dental Abutments ; Dental Stress Analysis ; methods ; Finite Element Analysis ; Humans ; Periodontal Ligament

Objective To investigate the status of nurses' resilience and to explore the related factors.Methods 1356 nurses from 11 level Ⅱ and level Ⅲ hospitals of Guangzhou were assessed by using the general information questionnaire and the Chinese version of Conner-Davidson resilience scale.Results The score of nurses' resilience was(59.99±13.59)points and it was significantly lower than that of the domestic norm.There was statistical difference of the score of nurses' resilience on different genders,educational background,professional titles,hospital level and night shifts.There was a positive correlation among educational background,night shifts and nurses' resilience,and a negative correlation between hospital level and nurses' resilience.The hospital level,night shifts and educational background were the influencing factors of nurses' resilience.Conclusions The level of nurses' resilience is low.The higher hospital level and educational background,and the less night shift,the higher of nurses' resilience.

The thrombolytic therapy has been widely used in treating acute cerebral infarction (ACI), but various severe complications restrict its clinical application. However, Chinese medicine shows its advantages in the treatment of ACI after thrombolytic therapy. Qi benefiting and blood activating method is an important principle and mean for supporting the vital qi and removing the surplus evil. By using this method, its short-term and long-term efficacy could be improved after thrombolytic therapy.
Cerebral Infarction ; drug therapy ; Drugs, Chinese Herbal ; therapeutic use ; Humans ; Medicine, Chinese Traditional ; methods ; Thrombolytic Therapy

Objective To develop the Chinese version of Attribution Questionnaire-27 and examine its replicability,reliability and validity.Methods The questionnaire was translated using the standard translation/back-translation method and examine its replicability,reliability and validity in 230 medical students who were selected by convenient method.Results The Cronbach α coefficient for Attribution Questionnaire-27 was 0.82 and ranging between 0.55 and 0.84 for the subscales.The test-retest reliabilities of the total scale was 0.77 and the subscales was between 0.61 to 0.81 after one week.Confirmatory factor analysis confirmed the hypothesized six factors attribution of responsibility model (x2/df=3,GFI=0.925,NFI=0.880,CFI=0.856,IFI=0.761,RMSEA=0.094) and three factors dangerous model (x2/df=1.773,GFI=0.959,NFI=0.941,CFI=0.973,IFI=0.973,RMSEA=0.058).The path analysis results support the existing theoretical assumptions.Condusions The Chinese version of Attribution Questionnaire-27 has good reliability and validity and can be used in medical student.

Objective:To describe the current situation in the nursing practice and their turnover intention in township health centers, and to analyze the changing potential influence in the nursing practice scope and workloads on their intention to leave those health centers. Methods:By means of a questionnaire, we conducted a survey on 167 nurses and interviewed 44 of them, all from 45 township hospitals within three provinces in China. Results:Since the healthcare system reform, the nursing workload in the township health centers significantly increased. 62% of the re-spondents considered their workload as heavy. Typically, the nursing work accounted for about 60% and the public health service work accounted for only 21% of the working hours. About 30% of the respondents were intended to leave their current job. The participating public health service was associated with intention to leave the job after con-trolling the province, workload, marital status, formal position, educational level and length of nursing service (P<0. 05). Conclusions:Since the healthcare system reform, the nursing practice scope in township health centers has been expanded and the workload increased considerably. But so far, expanding the scope of the nursing work may have potentials in reducing the intention of nurses to leave their current positions.

Objective To compare the image quality and radiation dose of prospective electrocardiogram(ECG)-triggered high-pitch spiral scan,prospectively triggered sequential scan and retrospectively triggered spiral scanning mode by dual-source CT in the follow-up of coronary artery bypass graft(CABG).Methods Totally 90 patients with stable heart rate(≤65 beats per minute)after bypass surgery were randomized to undergo prospective high-pitch spiral scan in group A (n=30),prospective sequential scan in group B (n=30),and retrospective spiral scan in group C (n=30).The patency and image quality of the grafts were blindly evalua-ted by two independent readers.Moreover,radiation dose of the three modes were evaluated.Results Scanning time of group A was significantly shorter than that of group B and group C (P<0.05).The average image quality score had no significant difference among three groups(H=0.449,P=0.799).The effective radiation dose of group A,group B and group C were (2.64±1.21)mSv, (6.48±2.58)mSv and(18.95±7.16)mSv,which was significantly lower in group A(H=101.21,P=0.00).Conclusion In pa-tients with a stable HR of 65 beats per minute or less,high-pitch spiral CT scan provides similar image quality at lower radiation dose compared with sequential scan and retrospective spiral scan,which can be widely used as a non-invasive effective tool for the post-operative follow-up of CABG.

OBJECTIVETo study the distribution patterns of stresses induced in bone tissue surrounding solely and splinted implants under dynamic loads.

METHODSThree dimensional finite-element models were created of two 765 sections of the mandible with solely or splinted implants embedded in. Vertical and oblique dynamic loads were applied in a circle of mastication (0.875 s). The stress distribution was analyzed to study the biomechanical behavior of bone tissue surrounding solely or splinted implants.

RESULTSAs loading on the solely implant 5, the maximum von Mises value in the surrounding bone tissue under oblique loads at 0.300 s was 4.2 times as much as that under vertical loads at 0.150 s. Meanwhile, as coincidently loading on the splinted implants, the maximum von Mises value at 0.300 s was 1.2 times as much as that at 0.150 s. As loading on the solely implant 5, the maximum stress value was 48.393 MPa at 0.300 s. As separately loading on the splinted implant 5, the maximum stress value of the whole model was 9.541 MPa in the same loading course, and the maximum stress was located at the distal cervical of the indirectly loaded implant 7. When loading on the pontic, the stress in bone tissue surrounding implant 7 was more than that of implant 5.

CONCLUSIONSStress in the bone-interface of the splinted implants is evenly distributed at the cervical level, which may also reduce disadvantages from oblique loads.

Adult ; Dental Implants ; Dental Stress Analysis ; Denture, Partial, Fixed ; Finite Element Analysis ; Humans ; Male ; Mandible ; physiology

OBJECTIVEThree-dimensional finite method was used to analyze stress and strain distributions of periodontal ligament of abutments under dynamic loads.

METHODSFinite element analysis was performed on the model under dynamic loads with vertical and oblique directions. The stress and strain distributions and stress-time curves were analyzed to study the biomechanical behavior of periodontal ligament of abutments.

RESULTSThe stress and strain distributions of periodontal ligament under dynamic load were same with the static load. But the maximum stress and strain decreased apparently. The rate of change was between 60%-75%. The periodontal ligament had time-dependent mechanical behaviors. Some level of residual stress in periodontal ligament was left after one mastication period. The stress-free time under oblique load was shorter than that of vertical load.

CONCLUSIONThe maximum stress and strain decrease apparently under dynamic loads. The periodontal ligament has time-dependent mechanical behaviors during one mastication. There is some level of residual stress left after one mastication period. The level of residual stress is related to the magnitude and the direction of loads. The direction of applied loads is one important factor that affected the stress distribution and accumulation and release of abutment periodontal ligament.

Denture, Partial, Fixed ; Finite Element Analysis ; Humans ; Incisor ; Mandible ; Mastication ; Periodontal Ligament ; Tooth

OBJECTIVEA reliable method for genotyping blood group antigens Dib, k, Jsb1910 and Jsb2019 was developed. Through screening for rare blood types, the National Rare Blood Bank of China may be enriched.

METHODSThe controls for allele detection of blood groups Dib, k, Jsb1910 and Jsb2019 were prepared via polymerase chain reaction (PCR)-mediated gene site-directed mutagenesis (SDM) technique. Sequence-specific primers were designed according to known single nucleotide polymorphism (SNP) sites of alleles of blood groups antigens Dib, k, Jsb1910 and Jsb2019, a multiplex PCR system was developed by optimizing PCR reaction system. And 4190 random healthy donors samples were screened for the blood group antigens.

RESULTSUsing SDM technique, controls for alleles in blood group Dib, k, Jsb1910 and Jsb2019 were successfully generated. And a multiplex PCR system for genotyping above blood groups was developed. After verification, the system has performed with good stability and reproducibility. Two Di (b-) samples have been discovered from 4190 samples, no k- and Js(b-) sample was found.

CONCLUSIONMultiplex PCR features rapid detection, high throughput and low cost, and can be used for screening for donors of rare blood types. Information of donors may be registered in a database, which in turn can help those with rare blood types or require long-term blood transfusion to obtain matched blood, thereby reduce the adverse reactions of blood transfusion.

Blood Group Antigens ; genetics ; Erythrocytes ; immunology ; Genotyping Techniques ; Humans ; Multiplex Polymerase Chain Reaction ; methods ; Mutagenesis, Site-Directed ; Polymorphism, Single Nucleotide

OBJECTIVE: To investigate the relationship between the perfusion CT features and the clinicopathologically determined prognostic factors in advanced gastric cancer cases. MATERIALS AND METHODS: A perfusion CT was performed on 31 patients with gastric cancer one week before surgery using a 16-channel multi-detector CT (MDCT) instrument. The data were analyzed with commercially available software to calculate tumor blood flow (BF), blood volume (BV), mean transit time (MTT), and permeability surface (PS). The microvessel density (MVD), was evaluated by immunohistochemical staining of the surgical specimens with anti-CD34. All of the findings were analyzed prospectively and correlated with the clinicopathological findings, which included histological grading, presence of lymph node metastasis, serosal involvement, distant metastasis, tumor, node, metastasis (TNM) staging, and MVD. The statistical analyses used included the Student's t-test and the Spearman rank correlation were performed in SPSS 11.5. RESULTS: The mean perfusion values and MVD for tumors were as follows: BF (48.14+/-16.46 ml/100 g/min), BV (6.70+/-2.95 ml/100 g), MTT (11.75+/-4.02 s), PS (14.17+/-5.23 ml/100 g/min) and MVD (41.7+/-11.53). Moreover, a significant difference in the PS values was found between patients with or without lymphatic involvement (p = 0.038), as well as with different histological grades (p = 0.04) and TNM stagings (p = 0.026). However, BF, BV, MTT, and MVD of gastric cancer revealed no significant relationship with the clinicopathological findings described above (p > 0.05). CONCLUSION: The perfusion CT values of the permeable surface could serve as a useful prognostic indicator in patients with advanced gastric cancer.
Adult ; Aged ; Female ; Humans ; Lymphatic Metastasis ; Male ; Microcirculation ; Middle Aged ; Prognosis ; Prospective Studies ; Regional Blood Flow ; Stomach Neoplasms/*blood supply/pathology/*radiography ; *Tomography, X-Ray Computed